This invention relates to an apparatus employing intumescent materials for stopping the spread of fires through openings occupied by plastic pipes.
Pipes, other conduits and service penetrations must pass through internal dividers, such as floors and walls of buildings. Openings must be left for such pipes and conduits when pouring concrete, for example. These openings are typically larger than the pipes themselves. The existence of such openings decreases fire resistance of walls and floors between adjacent units.
Metallic service penetrations do not achieve the desired fire resistance. Thermal conductance leads to a potential for fire to pass through walls or floors by igniting new fires on the unexposed side of the divider. However, a greater problem exists when plastic pipes are used because the pipes themselves are not fire resistant. A fire may cause the pipes to melt and smoke and fire can pass through the resulting openings and thus through the divider.
For this reason, plastic pipes have not been widely used in buildings where such a requirement for fire resistant internal dividers exists.
It is known to fill up the space between the divider and a plastic pipe with an intumescent material. These are materials which expand upon exposure to heat of an intensity typical of fires. A flat strip of the intumescent material may be formed into an annular shape and fitted about the pipe at the opening in the divider. The heat resulting from a fire causes the intumescent material to expand and, in theory, fill up the void left by the melted pipe. However, the design and construction of such pipe openings must be done with care to assure that they will function as required. Separate certification of each different configuration of opening is frequently required. This certification process has prevented the widespread adoption of plastic pipes in combination with intumescent materials for such applications as apartment buildings.
Attempts have been made to provide standard fittings for closing off openings for plastic pipes or the like. For example, a fire barrier of this type is disclosed in U.S. Pat. No. 4,221,092 to Johnson. In this patent, an intumescent material is located within an annular channel of a metal member fitted within the opening of a barrier. However, the construction requires the metal member to be sized for the particular opening in the barrier and a close fit is required between the metal member and the particular plastic pipe.
Another fire-proof device of the type is disclosed in U.S. Pat. No. 4,109,423 to Perrain. However, in this case a mechanical device including shutters is used to close off the opening. Such devices may be relatively expensive and subject to jamming if, for example, wet concrete or gout gets into the shutters.
U.S. Pat. No. 4,559,745 to Wexler shows another device for fire stopping of plastic pipes. This patent again relies on a mechanical device, namely a coil spring, to close off the opening.
It is an object of this invention to provide an apparatus for closing off openings for plastic pipes in the event of a fire which can be pre-certified as a unit and will fit a range of different sized openings through barriers.
It is a further object of the invention to provide an apparatus of the type which sealingly engages plastic pipes to stop initial passage of smoke through the opening around the pipe and yet will fit about pipes having different diameters within a limited range.
It is a further object of the invention to provide a fire resistant barrier including a structural member, panels on each side of the structural member, openings in the panels, a plastic pipe passing through the barrier at the openings and apparatuses on at least one side of the barrier employing an intumescent material to seal the openings in the event of fire on one side of the barrier.